^ Confirmed. Wiimmfi only needs a DNS entry on your DNS to direct internet traffic there.
Oh, and any Friend Codes on any of your games will be null/void at this point, so when you go to connect to Wiimmfi with a game, you need to clear all of your old Friend Codes off of the game first - otherwise it will throw you an error. And in Mario Kart DS, it will literally lock the game up and you'll have to power off and back on again. The reason is that when you connect to "Nintendo Wi-Fi" with ANY game, the first thing it will do is verify your Friend Code (this will change when you connect to Wiimmfi) and then verify all of the other Friend Codes you have saved on that game. Any one of them that doesn't verify will throw out an error and kick you off the network.
Oh, it most certainly does. I've done it - had people over to my town and I've visited at least one other person's town as well with a legitimate Nintendo DS and an old Wi-fi Router I still have that I first bought back in 2006. In fact, I used that router all the way until 2011 when I left the U.S. Military and ended up upgrading to a much newer, much faster home router. I kept the old router in its box, though, so when I wanted to set up Wiimmfi, I pulled it back out and set it up for the DS wi-fi (newer Wi-Fi security standards are unavailable on the DS).